Door closing apparatus



Feb. 14, 1961 R, VSTER ETAL 2,971,212

noR CLOSING APPARATUS 3 Sheets-Sheet 1 Filed Oct. 17, 1956 JSJ 13352757 'ff 10 775 e .f7 .m offiz fr 5.3 J4

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WALTER MLA-AN? SUI/11D Feb 14, 1961 R. vsTER ETAL 2,971,212

DOOR CLOSING APPARATUS 47 AY/5J 27 2a' .fa -fa' 26 la 7,1.: y j

1N VENTOR Feb. 14, 1961 R, VSTER E TAL 2,971,212

DOOR CLOSING APPARATUS Filed Oct. 17, 1956 3 Sheets-Sheet 3 United States DOOR CLOSING APPARATUS Filed Oct. 17, 1956, Ser. No. 616,549

. Claims priority, application Germany Oct. 18, 1955 24 Claims. (Cl. 16-55) The present invention relates to a door closing apparatus.

`More particularly, the present invention relates to an apparatus which is adapted to be connected to a door which is hingedly mounted at one side thereof and which automatically closes the door after the door is opened, the door being opened in resistance to the action of the door closing apparatus.

With conventional door closing apparatus of the above type, almost no resistance is provided to the opening of the door during the initial part of the opening thereof so that it is very easy for the wind, for example, to blow a door open through a relatively small angle with the conventional apparatus. Furthermore, the conventional apparatus must be specially designed for use with right or left hand doors, and the same apparatus cannot be used with both right hand and left hand doors. Also, the conventional door closing apparatus cannot operate etliciently through a wide range of temperatures. For example, in the wintertime the operation of a conventional doorv closing apparatus is much more difficult to carry out than in the summertime.

One of the objects of the present invention is to overcome the above drawbacks by providing a door closing apparatus which will provide resistance to the opening of a door which is substantially constant while the door is being opened through a certain angle and which gradually diminishes during further opening of the door.

Another object of the present invention is to provide a door closing apparatus which may be easily adapted for use with either right or left hand doors.

A further object of the present invention is to provide a door closing apparatus which is capable of operating reliably through a wide range of temperatures.

An additional object of the present invention is to provide a door closing apparatus which may have its parts easily adjusted so as to cancel out lack of accuracy in the manufacture of the parts.

Still another object of the present invention is to provide a door closing apparatus which may be easily adjusted with respect to a floor or ceiling in which the apparatus is carried.

A still further object of the present invention is to provide a door closing apparatus capable of accomplishing all of the above objects and at the same time composed of simple and ruggedly constructed elements which are very reliable in operation and which are inexpensive to manufacture and assemble.

Also, the objects of the present invention include a means for releasably maintaining a door in an open posi- Vtion with a door closing apparatus of the above type.

With the above objects in View the present invention mainly consists of a door closing apparatus which includes a support means and a crank turnably carried by the support means and adapted to be connected to a door. A means is connected to this crank for providing a sub- `stantially constant resistance to the opening of a door from a closed position thereof and to provide a resistance arent Vwhichgradually diminishes during the further opening of the door. Y

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

Fig. l is a longitudinal sectional View of a door closing apparatus according to the present invention;

Fig. 2 is a top plan view of a door closing apparatus according to the present invention with .the cover thereof removed;

Fig. 3 is a transverse sectional view of the door closing apparatus of Figs. 1 and 2;

Fig. 4 is a partly sectional sideelevational view of a door closing apparatus according to the present invention;

Fig. 5 is a longitudinal sectional view of a iluid brake arrangement used in the door closing apparatus of the present invention;

Fig. 6 is a graph illustrating the operation of the door closing apparatus of the invention;

Fig. 7 is a plan View of another embodiment of a door closing apparatus according to the present invention, the cover being removed from the apparatus of Fig. 7;

Fig. 8 is a transverse sectional view of the structure of Fig. 7;

Fig. 9v is a fragmentary top plan view of the end portion of the structure of Fig. 7 which includes the crank, part of a structure for releasably holding the door in a partly opened position being shown in section in Fig. 9;

Fig. 10 is a top plan view of a third embodiment of an apparatus according to the present invention with the cover removed;

Fig. 11 shows the structure of Fig. l() in a different position thereof;

Fig. l2 is a graph of the operation of the embodiment of Figs. l0 and ll; and

Fig. 13 is a diagrammatic illustration of the structure of Figs. l0 and l1.

Referring to Figs. l and 2 of the drawings, the door closing apparatus of the invention includes a support means composed in part of an outer housing l which may be made, for example, of sheet metal and. which may be enclosed in a floor or ceiling. At the left end of the housing 1, as viewed in Fig. 1, the bottom wall of the latter is provided with threaded openings which receive screws 2, two screws being provided at the left side of the housing 1, as is evident from Fig. 2, and these screws being turnable from the top ends thereof, as is also evident from Fig. 2. The bottom free ends of the screws 2 which extend downwardly beyond the bottom wall of the housing 1 respectively carry disks 3. Thus, the screws 2 and disks 3 provide an adjusting means: which enables the left end of the housing 1 to be adjusted in elevation so that the housing 1 can be accurately located in a h0rizontal position. The top open end of the housing 1 is closed by a cover 4, and this cover 4 is located in the plane of the floor or ceiling which receives the door closing apparatus.

The support means further includes an inner housing 5 which is open at its top and which is placed within the outer housing 1 in such a way that an elongated gap remains between the left side of the inner housing 5 and the left side of the outer housing 1, as is evident from Fig. 2, so that the screws 2 are accessible through this gap. The housing 5 rests on suitable brackets or the like 6 located at the four corners of the housing 1 and these brackets 6 are fixed to the housing 1. The housing 5 is fixed by screws to the brackets 6, and these screws extend through openings S, respectively, which are respectively located at the four corners of a flange 7 of the housing 5. larger than the diameters of the screws which pass therethrough, and inasmuch as the size of the h ousing is smaller than the size of the housing 1 so asl to provide a gap all around the housing 5 within the housing 1, it is possible before the screws extending through the openings 8 are tightened to shift the housing 5 within the housing 1 until the housing 5 is in its proper position, and then the screws are tightened. The upper open portion of the housing 5 is closed by a cover arrangement which includes a pair of cover members 9 and 10 which together completely cover the housing 5. As is apparent from Fig. 2, the housings 1 and 5 are elongated, and the cover members 9 and 10 overlap each other in a direction extending transversely across the housings.

A crank 11, which is adapted to be connected in any suitable way to a door, is turnably carried by the housing 5, and for this purpose the bottom wall portion of the housing 5 which is formed with an opening which receives the bearing 12 which turnably supports the crank 11 is thickened, as is apparent particularly from Fig. l. The crank 11 is provided with a crank portion extending radially therefrom in the interior of the housing 5, and the non-circular free end portion of the crank 11 which is located at the exterior of the housing 1 projects through a roller bearing of conventional construction secured in cover member il@ and is adapted to be connected to an unillustrated lever which is in turn connected to the door. Within the housing 5 a disk 13 is xed to the crank for rotation therewith, for a purpose described below, and the crank 11 is provided with the crank portion 14 which receives the pivot pin 16 which serves to pivotally connect to the crank portion 14 an elongated member 15 which forms a link of a linkage according to the present invention. As is apparent from Fig. 2, the portion of the link 15 which is located next to the pivot pin 16 is of an arcuate conguration, and when the crank 11 turns in a counterclockwise direction, as viewed in Fig. 2, through approximately 180, this arcuate portion of the link 15 becomes located between the disk 13 and the crank portion 14 and partly surrounds the crank 11 through an angle of approximately 180, as is indicated in broken lines in Fig. 2. rlfhe floor of the housing'5 is provided with another thickened portion adjacent the crank 11, and this other thickened portion is formed with a bore 17 which receives a stationary pivot pin 1S on which a second link 19 of the linkage of the invention is turnable. The link 19 is pivotally connected to the link 15 by the pivot pin 20. In accordance with the present invention, when the door connected to the crank 11 is closed, the Vparts have the position indicated in Fig. 2, and it will be noted that in this position of the parts the turning axis of the crank 11 as well as the axes of the pivot pins 18 and 20 are all located substantially in a common plane, while the crank portion 14 makes an acute angle with this plane. As a result of this arrangement, as will be apparent from the description below, when the door is initially opened through a predetermined angle there is a substantially constant resistance to the opening thereof and this resistance gradually diminishes as the door is opened beyond this predetermined angle.

It will be noted that the crank 11 together with its crank portion 14 as well as the links 15 and 19 all cooperate together to form a linkage system similar to a parallelogram linkage. The turning axes of the cranks 11 and 19 are stationary while the pivotal connections between the links 15 and 19 and the link 15 and the crank portion 14 are shiftable.

A spring means which includes a coil spring 21 is provided to cooperate with the linkage means of the Vinvention in order to urge the crank 11 to turn in that direction which closes the door. The: end of the spring The diameters of the openings S are 21 which is distant from the linkage means s mounted on a pin 22 which is fixed in the interior of the housing 5 in the manner shown most clearly in Fig. 1, so that the pin 22 forms a mounting means for mounting the spring 21.

The end of the spring 21 distant from the mounting pin 22 is connected to an intermediate member 23 formed with an opening through which a threaded free end portion of a rod 25 freely passes, this threaded portion of the rod 25 carrying a nut 24 which bears against a part of the intermediate member 23, so that by adjusting the position of the nut 24 on the rod 25 the position of the intermediate member 23 with respect to the rod 25 can be regulated. The end of the rod 25 distant from the intermediate member 23 is pivotally connected by the pivot pin 2G to the link 19.

The link 15 extends beyond the pivot pin 20, and a pivot pin 26 serves to connect to the link 15 a piston rod 27 of a tluid brake means. The housing of the fluid brake means is mounted on the housing 5 for pivotal movement through the medium of a pin 28'similar to the pin 22 and pivotally supporting the housing of the brake means.

This brake means includes an inner cylinder 29 (Fig. 5) and a concentric outer cylinderl 30 which is spaced from and which surrounds the cylinder 29 so as to form an elongated tubular chamber therewith. The cylindrical members 29 and 30 are interconnected with each other in a huid-tight manner. Thus, an end wall 31 is thread-V edly carried by one end of the cylinder 29 and another hexagonal end Wall 32 is threadedly carried by the other of the ends of the cylinder 29, and the outer cylinder 30 is gripped in a Huid-tight manner between these end walls.

A tubular insert 33 extends into a recess at the inner face of the end wall 32, this insert 33 communicating with the interior' of the inner cylinder 29, and, as 1s evident from Fig. 5,v anY annular ange is xed to and extends outwardly from the insert 33 and is gripped at its outer periphery between the wall 32 and the left end of the cylinder 29, as viewed in Fig. 5, so that this flange provides a Huid-tight connection between elements 29 and 32. The tubular insert 33 is formed with an axial bore passing therethrough which is coaxial with the cylinder 29, and the right end ofthe bore of the tubular insert 33, as viewed in Fig. 5, is narrowed so that it acts as a valve seat for a valve member 34 of substantially cylindrical configuration which is axially slidable within the insert 33, the left end of the valve member 34 being adapted to extend to the left beyond the insert 33 into a passage formed in the end wall 32, as is evident from Fig. 5. The left end of the valve member 34 engages the tapered substantially conical end of an adjusting screw 35 which is threadedly carried by the end wall 32 and which is mounted in the latter in a duid-tight manner with suitable sealing rings, so that by turning the screw 35 the axial position thereof in the wall 32 is adjusted and the extent to which the valve member 34 is shit'table to the left in the insert 33, as viewed in Fig. 5, is adjusted'. The valve member 34 is formed at its periphery with longitudinally extending axial grooves which extend along the entire length of the valve member 34, and the insert 33 is provided in its interior next to its narrowed portion with an annular groove communicating` through the longitudinal grooves of the Valve member 34 with the hollow inner space of the wall 32 which accommodates the bot tom tapered end of the adjusting screw 35. This space in the interior of the wall 32 which communicates with the grooves of the valve member 34 also communicates with a passage 36 which leads to the chamber formed between the cylinders 29 and 3).

The valve member 34 is preferably made out ofla material such as a synthetic plastic or the like which has a coefficient of thermal expansion which permits the diameter of the valve member 34 `to change in correspondence with changes in the viscosity of a braking earners liquid in the cylinder 29 so that Substantially the same operating conditions exist through a wide range of temperatures. In this way, the cross sectional areas of the passages formed bythe grooves of the valve member 34 become greater in summer and smaller in winter-so as to adapt the iiow of liquid to the temperature changes. Any suitable material capable of accomplishing the above results may be used for the valve member 34, such as phenol formaldehyde, melamine formaldehyde, or urea formaldehyde.

A hollow piston 37 is fixed to the piston rod 27 and carries a pair of piston rings 38 which slidably engage the inner face of the cylinder 29 to provide a slidable sealed engagement between the piston and cylinder 29, these piston rings being axially spaced from each other by as large a distance as is made possible by the length of the piston 37. The piston 37 is formed with openings passing therethrough, and non-return valves 39 shown in the form of ap valves are carried by the piston 37 and cooperate with the openings passing therethrough so that when the piston 37 moves to the right, as viewed in Fig. 5, the non-return valves open to allow the liquid to ow freely through the piston when the piston 37 shifts to the left, as viewed in Fig. 5, the non-return valves 39 are closed so that fluid cannot then pass through the piston to the opposite side thereof.

The right end of the cylinder 29, as viewed in Fig. 5, is formed with a cutout 40 providing free communication between the interior of the cylinder 29 and the chamber formed between the latter and the cylinder 30, and approximately at the center of the cylinder 29 the latter threadedly carries an insert 41 provided with an opening of predetermined size passing therethrough and also pro viding communication between the interior of the cylinder 29 and the space within the cylinder 30 surrounding the cylinder 29. The cylinder 30 removably carries a plug 42 directly over the insert 41. This plug 42 may threadedly engage the cylinder 30 and can be removed so that the insert 41 may be replaced by another insert having an opening of a different size, so that in this way means is provided for regulating the size of the opening at the intermediate part of the cylinder 29. By changing the size of the opening of the insert 41 the speed of return movement of the piston 37 during the return of the parts to the solid line position thereof shown in Fig. 2 can be regulated.

As is apparent from Fig. 4, the end wall 32 is formed with an additional passage 43 which communicates at one end with the interior of the cylinder 29 and at its opposite end with the chamber between the cylinders 29 and 30. The flange extending from the insert 33 (Fig. 5)

is formed with a plurality of bores 44 passing therethrough, and these bores all communicate with an annular groove formed in the right face of the end wall 32, as viewed in Fig. 5. This annular groove in turn communicates with one end ofthe passage 43 shown in Fig. 4, so that in this Way the interior of the cylinder 29 communicates with the passage 43. It will be noted, more particularly, that the interior portion of the cylinder 29 to the left of the piston 37, as viewed in Figs. 4 and 5, communicates with the passage 43. The end wall 32 also carries a spring pressed safety valve 45 which communicates with the passage 43, and a screw member 46 is threadedly carried by the end wall 32 to adjust the pressure of the spring of the safety valve.

A lug 47 is fixed to and extends axially from the hexagonal end wall 32 and is formed with an opening through which pivot pin 28 passes, so that in this way the pivot pin 28 provides a mounting means fixed to the housing 5 for mounting the above described brake means.

As is apparent from Fig. 3, the cover member 9 threadedly carries a plug 48 which is located directly over the adjusting screw 35, the head of the plug 48 being located Within a suitable opening formed in the cover 4. When the plug 48 is removed, the operator may turn the screw 35 so as to adjust the operation of' the valve 34, and in this Way the closing speed of the door during the last 30 of the closing thereof, for example, may be regulated.

As is apparent from Fig. 2, the housing means 1, 5 is elongated and has a longitudinal central axis. As may be seen from Fig. 3, the cover member 9 is provided with another opening similar to the opening which receives the plug 4S and symmetrically located with respect to the longitudinal axis of the housing means. This other opening, which is shown at the right of the plug 48 in Fig. 3, threadedly receives a second plug 49 which has its head end directed downwardly, as viewed in Fig. 3. It will be noted that the cover 4 is not provided with any opening which is located over the plug 49. This second plug is used when the door closing apparatus is connected to a right hand door rather than a left hand door, for example.

For the same reason, it will be noted from Fig. 2 that the housing 5 is provided with a second opening 12 in addition to the opening 12 which supports the crank 11, and also a second opening 17 is provided in addition to the opening 17 which fixedly supports the pivot pin 13. The openings 17 and 12 on each side of the longitudinal axis of the housing means are arranged so that they are symmetrical. That is, the openings 17 are symmetrical with respect to the longitudinal axis, and the openings 12 are symmetrical with respect to the longitudinal axis, as is evident from Fig. 2. As a result of this arrangement the crank 11 and the pivot pin 18 may be shifted from one to the other side of the longitudinal axis, and the links 15 and 19 may be turned through 180 in order to be assembled with the crank 11` and the pivot pin 18, respectively. Furthermore, the brake means and spring means may be interchanged so that the spring 21 is mounted by the pin 28 and the lug 47 is pivotally supported by the pin 22. When this is done, the position of the cover 9 is not changed, and instead the plug 48 is inverted and the plug 49 is also inverted so that this plug 49 is now located over the adjusting screw 35 in order to give access thereto.. In this event the cover member `4 is exchanged for another cover member which is provided with suitable openings to receive the head end of the plug 49 as well as to accommodate the portion of the crank 11 which extends outwardly beyond the support means. The cover member 10 need only be turned through 180 and may therefore be used when the parts are located at either side of the longitudinal axis. The disk 13 and the crank portion 14 are provided with additional openings to receive the pivot pin 16 to locate the latter properly when the parts are changed from one to the other side of the longitudinal axis of the housing means 1, 5.

Thus, with the above described structure, it is unneccessary to use the apparatus either for right hand doors or for left hand doors. The same apparatus can be adapted for use with either right or left hand doors simply by rearranging the parts as described above.

As is apparent from Figs. l and 2, the door closing apparatus may be provided with a means for releasably maintaining the door in a partly opened position. For example, the crank 11 may be releasably maintained in the position to which it has moved after turning through To accomplish this result the cover 9 carries a housing 50 of a box-like conguration which serves as a guide means for a slide member 51 which is urged by a spring 52 to the right, as viewed in Figs. l and 2, this spring engaging the left wall of the housing 50 and the left face of the slide member 51. This slide member 51 turnably carries a roller 53 which bears against the outer peripheryof the disk 13. This disk 13 is formed in its outer periphery at a predetermined part thereof with a notch 54 into which the roller 53 is urged by the spring 52 after the disk 13 together with the crank 11 turn through the desired angle.

andinia;

I n" order` to be able to render the releasable holding meansl idle whenever desired, the slide member l is xed to one end of a rod 5S which extends through the spring 52 and outwardly beyond the housing 5t? where the free end of the rod 55 carries a projection in the form of a disk or washer 56 which extends laterally beyond the rod 55. The cover member 9 turnably supports a crank pin 57 which may be turned by the operator to and from a position where the crank pin 57 is located between the projection 56 and the housing 5d so that in the solid line position of the crank pin 5? shown in Fig. 2 the spring 52 cannot shift the slide member .'Sl to the right, as viewed in Fig. 2, and thus the roller 53 will not enter the notch 54. When the apparatus of Fig. 2 is associated with a door which opens to the right, the releasable holding means shown in Fig. 2 cannot participate in the operation of the device.

When a door connected to the above-described apparatus is opened, the crank ll turns in a counterclockwise direction, as viewed in Fig. 2, and the spring 2li becomes tensioned. At the same time the piston 37 slides within the cylinder 29 and the liquid within the cylinder 29 flows through the valves 39 from the right to the left side of the piston 37, as viewed in Fig. 5. This liquid also tlows through the openings `ttl and it into the charnber between the cylinders 29 and Sti. The abovedescribed linkage and the connection ot the spring means and the brake means thereto permits the crank ll to be turned through approximately 180, and in the end position of the crank il the parts associated therewith have the broken line positions indicated in Fig. 2. At this time the piston 37 has moved through a stroke of approximately 8 centimeters, for example. When the door is closed by the tensioned spring 2l, the liquid in the cylinder 29 which, is located to the left of the piston 37, as viewed in Fig. 5, freely flows through the opening of the insert 41 into the chamber between the cylinders 29 and 39 and from this chamber back through the opening lill to the other side of the piston 37, until the door is stili opened by an angle of approximately 30, liquid also flowing to the chamber between the cylinders 29 and Sti through the valve 34 and the passage 36. After the opening of the insert il is closed by the pistons 37 and during the time that the latter moves to the left beyond the insert 41, as viewed in Fig. 5, all of the oil flows from the cylinder 29 to the chamber between the latter and the cylinder 39 through the valve member 54- and the pas sage 36, so that by adjusting the single screw 35 it is possible to regulate the speed of closing of the door during the last portion of the closing thereof. It the door should be forcefully slammed or if a force in addition to the spring 21 acts to close the door, then the valve 45 opens So that additional oil tlows from the cylinder 29 through the passage 43, the screw 46 being available to adjust the force required to open the valve 45.

In the graph which is shown in Fig. 6, the angle of the opening of a door is indicated along the horizontal axis andthe force which the structure exerts to resist opening of the door and to urge the door to its closed position is indicated along the vertical axis. As may be seen from the solid line curve of the graph of Fig. 6, the above-described linkage means and the spring means therewith provide a substantially constant relatively great resistance to the opening of the door during the initial part of the opening thereof, and then during the further opening of the door the resistance to the opening thereof gradually diminishes and becomes zero as the door is opened to an angle which approaches lSO". On the other hand, during closing of the door the spring acts on the door with a gradually increasing turning moment shown by the same curve until at the nal portion of the closing of the door the greatest turning moment is applied by the spring 21 and this turning moment remains substantially constant during the last portion of the closing 30 the curve is concave in an upward direction. As a comparison with the manner in which the door of theY invention operates, the dotted line curve of the manner of operation of a conventional door is also shown in Fig. 6. It will be noted that the largest turning moment is provided with the dotted line curve when the door is opened by approximately 30, and during opening of the door this curve falls off very sharply and it falls ott again during the final portion of the closing of the door.

In the embodiment of the invention which is shown in Figs. 7-9, the crank 14 of the crank 1E' is composed of a pair of parts which carry the pivot pin 16 and between which an end of the link 15 extends, as is shown particularly in Fig. 8. The link 19 is replaced by a pair of identical levers 58 located one over the other and turnably supported by the pivot pin t8', these levers Srbeing in the form of bell cranks, as is particularly evident from Fig. 7. The pivot pin 20 is carried by the pair of levers 5S and extends through a portion of the link 15 which extends between the levers 58, so that in this way the levers 58 are pivotally connected to the link 15. At the ends of the levers 58 distant from the pivot pin 20', a compression spring means acts on the lever means 58 to urge the latter in a clockwise direction, as viewed in Fig.. 7. This compression spring means includes a compression spring 59 located between a pair of annular members 60 and 61 with a predetermined prestress. The annular member 60 is in the form of a ring which is lixed to a sleeve 62, and this sleeve y62 slidably receives a rod 63, so that elements 62A and 63 form a pair of telescoped members which guide the spring means, the annular member 6l surrounding and being slidable upon the rod 63. The sleeve 62 is xed to a rod provided at its left end, as viewed in Fig. 7, with an eye 64 which surrounds the pivot pin 22 so that in this way the latter serves to mount the spring means of Fig. 7. The rod 63 is provided with an enlarged end portion 63 against which the ring 61 is pressed by the spring 59, and the right end face of the enlarged portion 63 is formed with a recess so that it is of a substantially biturcated conliguration. The right end portion of the enlarged part 6-3 of the rod d3, as viewed in Fig. 7, extends between the levers 58, and the latter carry a pin 58 which is received between the bifurcations of the portion 63 in the recess of the latter, so that the levers 58 are urged in a clockwise direction, as viewed in Fig. 7, simply by the pressure of the portion 63 of rod 63 against the pin 58.

rthe sleeve 62 is formed with an opening 65, and the rod 63 is formed with a cross bore 66. When the compression spring means is to be assembled with the remainder of the apparatus, the rod 63 is pushed into the sleeve d2 until the opening 65 is aligned with the opening 65, and then a pin is passed through the opening 65 into the opening 66, this opening 65 being of a larger diameter than the opening 66, so that in this way the compression spring means is maintained in a compressed condition which makes it very easy to insert the same into the apparatus. After the compression spring means is assembled with the rest of the apparatus, the pin extending through the opening 65 into the opening 66 is removed.

It will be noted that with the embodiment of Figs. 7-9, the link 15 also extends beyond the pivot pin 2,0 and is pivotally connected to the piston rod 27 of the brake means which is identical with the brake means of the embodiment of Figs. 1 5, this brake means including the lug 47' formed with the opening through which pivot pin 23 passes, as indicated in Fig. 7.

As is particularly apparent from Figs. 8 and 9, the embodiment of Figs. 7-9 is provided also with a releasable holding means which is similar to that described above, but in this case the releasable holding means extends transversely of the housing rather than longitudinally thereof. Furthermore, it will be noted that with the embodiment of Figs. l and 2, the longitudinal axis along which the slide member 51 moves is spaced from the turning axis of the crank 11 by the greatest possible distance which permits the roller 53 to cooperate properly with the notch 54, and furthermore, the spring 52 urges the roller 53 in a direction which is opposed to the direction of movement of the periphery of the disk 13 during the opening of the door. With this arrangement of parts the holding means of Figs. 1 and 2 is capable of holding the door in its partly open position even though the spring 52 is considerably weaker than the spring 21. -In contrast, with the embodiment of Figs. 7-9, the spring 52 moves the slide member 51 along an axis which is radial with respect to the turning axis of the crank 11. The releasable holding structure, with the exception of the disk 13, used in Figs. 7, 8 and 9 is identical with that of Figs. 1 and 2 except for the above-described rearrangement of the releasable holding means and except for the fact that the releasable holding means is carried by the cover member 10 with the embodiment of Figs. 7, 8 and 9 rather than the cover member 9. The disk 13 is replaced by a split ring 67 which surrounds and is fixed in an angularly adjusted position with respect to the crank 11 by the screw 68 shown in Fig. 9, and this split ring 67 is provided with a notch 54 which receives the roller 53.

When a door connected to the apparatus of Figs. 7-9 is opened, the crank 11 turns in a counterclockwise direction, as viewed in Fig. 7, and during such time the spring 59 becomes compressed to a greater degree, the linkage means of the invention permitting the crank 11' to turn through approximately 180, and at the end of such turning the parts have the broken line position indicated in Fig. 7 where the arcuate portion of the link 15 partly surrounds the crank 11 through an angle of approximately 180. It will be noted that with the embodiment of Figs. 7, 8 and 9 the axes of the crank 11', the pivot pin 18', and the pivot pin 20 are also located substantially in a common plane and the crank portion 14 makes an acute angle with this plane in the position of the parts shown in Fig. 7, which corresponds to the closed position of the door. When the door is released, the spring 59 expands to return the parts to the solid line position indicated in Fig. 7 in order to close the door, and during this time the brake means resists the movement of the parts by the spring means.

In the third embodiment of the invention which is illustrated in Figs. 10-13, the link 19 of Fig. l is replaced by a member 19 which is of a substantially triangular configuration, this member 19 serving to interconnect the link 15 with the stationary pivot pin 18", in the same way as the link 19 of Fig. 1. Thus, the pivot pin 18 is connected to one corner of the member 19 While the link 15 is pivotally connected to another corner of the link 19'. The third corner of the link 19 is pivotally connected to a link 69 Whose end distant from the link 19 is pivotally connected to a relatively short link 70 whose end distant from the link 69 is pivotally connected to the member 71 which is xed to the spring 21 and forms a part of the spring means of the embodiment of Figs. 10-13. A crank 72 is pivotally carried by the support means for -turning movement about the stationary axis of the pivot lmember 71, or this member 71 may be formed with an elongated slot through which the right free end of the spring 21 freely passes. This member 71 threadedly carries an adjusting screw which engages the right end of the spring 21, so that by turning this adjusting screw, the eiective length of the member 71 may be regulated.

It will be noted that with the embodiment of Figs. 10-13 the axis of the crank 11, the axis of the pivot pin 18', and the axis of the pivotal connection between the link 69 and the plate 19' are all located substantially in a common plane when the door is closed, and the crank portion 14 of the crank 11 makes an acute angle with this plane, so that this embodiment of the invention produces substantially the same results as the above-described embodiment of the invention.

The spring 21 of the embodiment of Figs. 10-13 pulls on the linkage with a predetermined pretension of, for example, kg. When the door is fully opened, the tension of the spring increases to approximately 200 kg. The turning moment curve has the conguration shown in the graph of Fig. 12. During closing of the door the links 69 and 70 fold together between the plate 19 and the member 71. The link 69 is provided with a notch 75 at the side edge of link 79 which is directed toward the pivot pin 73, and when the structure moves from the door open position indicated in Fig. 1l to the door closed position indicated in Fig. 10, the pin 73 becomes located in the notch 75.

With the above-described structure of the invention, the force required to open the door is greatest during the initial part of the opening of the door and the force closing the door is greatest during the last part of the closing thereof, so that a doo-r is reliably closed with the structure of the invention. Furthermore, the feature of arranging link 15 so that it is capable of partly surrounding the crank 11 through approximately 180 enables the crank 11 to be very simply constructed so that it can extend along a straight line all the way down to the oor of the inner housing 5. Also, it will be noted that by extending the link 15 outwardly beyond its connection to the link 19, 19 or 58, the stroke of the piston of the brake means is maintained relatively large. It is apparent that this brake means may operate either with a gas such as air or with la liquid such as oil. Furthermore, the structure of the brake means presents the advantage of being composed of parts which need only be turned so as to be threaded together in order to assemble the elements of the brake means.

It should be noted that while the releasable holding means 50-54 of the embodiment of Figs. l and 2 can be used only with a door which opens in one direction, the arrangement of the releasable holding means according to the embodiment of Figs. 8 and 9 permits this releasable holding means to be used either with right or left hand doors.

It will be noted that the curve of operation of the ernbodiment of Figs. 10-13 has substantially the configuration of a hyperbola, as shown in Fig. 12. The additional linkage structure located between the plate 19 and the spring 21 of this embodiment of the invention together with the crank 72 prevents the force required to open the door during the initial part of the opening thereof from rising to infinity. Also, a compression spring may be used with the embodiment of Figs. 10-13 instead of a tension spring. Thus, a compression spring arrangement similar to that of Figs. 7-9 may be incorporated into the embodiment of Figs. 10-13, if desired.

It will be understood that each of the elements described above, or two or more together, may alsol find a useful application in other types of door closing apparatus diiering from the types described above.

While the invention has been illustrated and described as embodied in adjustable door closing apparatus, it is not intended to be limited to the details shown, since vari ous modifications and structural changes may be made without departing in any wayfrom the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, trom the stand 11 point of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should Aand are intended to`be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. ln a door closing apparatus, in combination, suppont means; linkage means carried by said support means and including a part adapted to be connected to a door; spring means carried by said support means and operatively connected to said linkage means for resisting the opening of a door connected to the latter; and uid brake means carried by said support means and operatively connected to said linkage means for retarding the movement thereof by said spring means,`said uid brake means including an inner cylinder, a piston slidabtle therein, an outer cylinder coaxial with and surrounding said inner cylinder and forming an elongated tubular chamber therewith, and a pair of end walls affixed to said inner cylinder, extending outwardly therefrom, and carrying said outer cylinder, one of said end walls being located adjacent said linkage means and the other of said end walls being iocated distant from said linkage means, said inner cylinder being formed adjacent said one end wall with an opening providing free communication between the chamber between said cylinders and the interior of said inner cylinder, and said inner cylinder also being formed with an intermediate opening located substantially centrally between the ends thereof and also providing communication between said chamber and the interior of said inner cylinder, said other end wall being formed with a passage providing communication between the interior of said inner cylinder and said chamber so that during movement of said piston away from said one end wall toward said other end wall tluid ilows from the space in the inner cylinder between said other end wall and said piston through said intermediate opening and said passage into said chamber, when the piston is located between said one end wall and said intermediate opening, while iluid flows from said chamber through said opening adjacent said one end wall into the space in the inner cylinder between said piston and said one end wall, whereas iluid ows from said inner cylinder to said chamber when the piston in said inner cylinder is located between said other end wall and said intermediate opening of said inner cylinder through said passage.

2. in a door closing apparatus, in combination, support means; linkage means carried by said support means and including a part adapted to be connected to a door; spring means carried by said support means and operatively connected to said linkage means for resisting the opening of a door connected to the latter; and uid brake means carried by said support means and operatively connected to said linkage means for retarding the movement thereof by said spring means, said fluid brake means including an inner cylinder, a piston slidable therein, an outer cylinder coaxial with and surrounding said inner cylinder and forming an elongated tubular chamber therewith, and a pair of end walls aiiixed to said inner cylinder, extending outwardly therefrom, and carrying said outer cylinder, one :of said end walls being located adjacent said linkage means and the other of said end walls being located distant from said linkage means, said inner cylinder being formed adjacent said one end wall with an opening providing free communication between the chamber between sad cylinders and the interior of said inner cylinder, and said inner cylinder also being formed with an intermediate opening located substantially centrally between the ends thereof and also providing communication between said chamber and the interior of said inner cylinder, said other end wall being formed with a passage providing communication between the interior of said inner cylinder and said chamber so that during movement of ,said Apiston away from said one end wall toward said other end wall Huid 'flows from the space in the inner cylinder between said other end wall and said piston through said intermediate opening and said passage into said chamber, when the piston is located between said one end wall and said intermediate opening, while fluid ows from said chamber through said opening adjacent said one end wall into the space in the inner cylinder between said piston and said one end wall, whereas uid flows from said inner cylinder to said chamber when the piston in said inner cylinder is located between said other end wall and said intermediate opening of said inner cylinder through said passage, a plug carried by said outer cylinder opposite said intermediate opening of said inner cylinder to give access to said intermediate opening, and means for changing the size of said intermediate opening.

3. in a door closing apparatus, in combination, support means; linkage means carried by said support means and including a part adapted to be connected to a door; spring means carried by said support means and operatively connected to said linkage means for resisting the opening of a door connected to the latter; and fluid brake means carried by said support means and operatively connected to said linkage means for retarding the movement thereof by said spring means, said uid brake means including an inner cylinder, a piston slidable therein, an outer cylinder coaxial with and surrounding said inner cylinder and forming an elongated tubular chamber therewith, and a pair of end walls affixed to said inner cylinder, extending outwardly therefrom, and carrying said outer cylinder, one of said end walls being located adjacent said linkage means and the other of said end walls being located distant from said linkage means, said inner cylinder being formed adjacent said one end wall with an opening providing free communication between the chamber between said cylinders and the interior of said inner cylinder, and said inner cylinder also being formed with an intermediate opening located substantially centrally between the ends thereof and also providing communication between said chamber and the interior of said inner cylinder, said other end wall being formed with a passage providing communication between the interior of said inner cylinder and said chamber so that during movement of said piston away from said one end wall toward said other end wall uid flows from the space in the inner cylinder between said other end wall and said piston through said intermediate opening and said passage into said chamber, when the piston is located between said one end wall and said intermediate opening, while fluid ilows from said chamber through said opening adjacent said one end wall into the space in the inner cylinder between said piston and said one end wall, whereas uid fiows from said inner cylinder to said chamber when the piston in said inner cylinder is located between said other end wall and said intermediate opening of said inner cylinder through said passage, a valve member carried by said other end wall in said passage formed therein for adjusting the flow of fluid through said passage, and an adjusting member threadedly carried by said other end -wail and having a tapered end engaging said Valve member for adjusting the position thereof in said other end wail.

4. ln a door closing apparatus, in combination, support means; linkage means carried by said support means and including a part adapted to be connected to a door; spring means carried by said support means and operatively connected to said linkage means for resisting the opening of a door connected to the latter; and iiuid brake means carried by said support means and operatively connected to said linkage means for retarding the movement thereof by said spring means, said uid brake means including an inner cylinder, a piston slidable therein, an outer cylinder coaxial with and surrounding said inner cylinder and forming an elongated tubular chamber therewith, and a pair of end walls aflixed to said inner cylinder,

Vextending outwardly therefrom, and carrying said outer cylinder, one of said end walls being located adjacent said linkage means and the other of said end walls being located distant from said linkage means, said inner cylinder being formed adjacent said one end wall with an opening providing free communication between the chamber between said cylinders and the interior of said inner cylinder, and said inner cylinder also being formed with an intermediate opening located substantially centrally between the ends thereof and also providing communication between said chamber and the interior of said inner cylinder, said other end wall being formed with a passage providing communication between the interior of said inner cylinder and said chamber so that during movement of said piston away from said one end wall toward said other end wall uid ows from the space in the inner cylinder between said other end wall and said piston through said intermediate opening and said passage into said chamber, when the piston is located between said one end wall and said intermediate opening, while fluid flows from said chamber through said opening adjacent said one end Wall into the space in the inner cylinder between said piston and said one end wall, whereas uid ows from said inner cylinder to said chamber when the piston in said inner cylinder is located between said other end wall `and said intermediate opening of said `inner cylinder through said passage, a valve member carried by said other end wall in said passage formed therein for adjusting the flow of fluid through said passage, and an adjusting member threadedly carried by said other end wall and having a tapered end engaging said valve member for adjusting the position thereof in said other end Wall, said valve member being slidable in an insert carried by said other end wall.

5. In a door closing apparatus, in combination, support means; linkage means carried by said support means and including a part adapted to be connected to a door; spring means carried by said support means and operatively connected to said linkage means for resisting the opening of a door connected to the latter; and fluid brake means carried by said support means and operatively connected to said linkage means for retarding the movement thereof by said spring means, said uid brake means including an inner cylinder, a piston slidable therein, an outer cylinder coaxial with and surrounding said inner cylinder and forming an elongated tubular chamber therewith, and a pair of end walls affixed to said inner cylinder, extending outwardly therefrom, and carrying said outer cylinder, one of said end walls being located adjacent said linkage means and the other of said end walls being located distant from said linkage means, said inner cylinder being formed adjacent said one end wall with an opening providing free communication between the chamber between said cylinders and the interior of said inner cylinder, and said inner cylinder also being formed with an intermediate opening located substantially centrally between the ends thereof and also providing communication between said chamber and the interior of said inner cylinder, said other end wall being formed with a passage providing communication between the interior of said inner cylinder and said chamber so that during movement of said piston away from said one end wall toward said other end wall fluid flows from the space in the inner cylinder between said other end wall and said piston through said intermediate opening and said passage into said chamber, when the piston is located between said one end wall and said intermediate opening, while fluid flows from said chamber through said opening adjacent said one end wall into the space in the inner cylinder between said piston and said one end wall, whereas uid ows from said inner cylinder to said chamber when the piston in said inner cylinder is located between said other end wall and said intermediate opening of said inner cylinder through said passage, a valve member carried by said other end wall in said passage formed therein for adjusting the flow of uid through said passage, said valve member being formed with fluid passage means extending the j j 14 length thereof, and an adjusting member threadedly carried by said other end wall and having a tapered end e11- gaging said valve member for adjusting the position thereof in said other end wall, said valve member being made of a material which has a coeicient of thermal expansion corresponding to the change in the viscosity of a brake liquid located in said cylinders due to temperature changes so that said valve member continues to provide substantially the same flow irrespective of temperature changes.

6. In a door closing apparatus, in combination, support means; linkage means carried by said support means and including a part adapted to be connected to a door; spring means carried by said support means and operatively connected to said linkage means for resisting the opening of a door connected to the latter; and fluid brake means carried by said support means and operatively connected to said linkage means for retarding the movement thereof by said spring means, said fluid brake means including an inner cylinder, a piston slidable therein, an outer cylinder Y coaxial with and surrounding said inner cylinder and forming an elongated tubular chamber therewith, and a pair of end walls aixed to said inner cylinder, extending outwardly therefrom, and carrying said outer cylinder, one of said end Walls being located adjacent said linkage means and the other of said end walls being located distant from said linkage means, said inner cylinder being formed adjacent said one end wall with an opening providing free communication between the chamber between said cylinders and the interior of said inner cylinder, and said inner cylinder also being formed with an intermediate opening located substantially centrally between the ends thereof and also providing communication between said chamber and the interior of said inner cylinder, said other end wall being formed with a passage providing communication between the interior of said inner cylinder and said chamber so that during movement of said piston away from said one end wall toward said other end wall uid flows from the space in the inner cylinder between said other end wall and said piston through said intermediate opening and said passage into said chamber, when the piston is located between said one end wall and said intermediate opening, while uid ows from said charnber through said opening adjacent said one end wall into the space in the inner cylinder between said piston and said one end wall, whereas duid ows from said inner cylinder to said chamber when the piston in said inner cylinder is located between said other end wall and said intermediate opening of said inner cylinder throguh said passage, said other end wall being formed with a second passage providing communication between the interior of said inner cylinder and said chamber, and a safety valve located in said other end wall and communicating with said second passage.

7. In a door closing apparatus, in combination, support means; a crank turnably carried by said support means for turning movement about a predetermined axis and adapted to be connected to a door; linkage means carried by said support means and operatively connected to said crank; spring means carried by said support means and operatively connected to said linkage means for resisting the opening of a door connected to said crank; a disk xed to said crank for turning movement therewith and being formed with a notch in its outer periphery; a roller engaging the outer periphery of said disk; a slide member turnably carrying said roller; guide means slidably guiding said slide member for movement toward and away from said disk between an active position and a retracted position; a second spring means acting on said slide member for urging the same toward said disk so that when said notch is aligned with said roller the latter is urged by said second spring means into said active position in which the roller carried by said slide member engages said notch for releasably maintaining a door connected to said crank in a predetermined opened position; a rod xed to said slide member and having a free end portion distant from said slide member; a projection xed to said free end portion of said rod and extending laterally therefrom; and a stop member movably carried by said support means for movement to and from a position located between said projection and slide member to hold said slide member in said retracted position and to prevent movement of said slide member by said second spring means in a direction which moves said roller into said notch when said stop member is in said position thereof.

8. In a door closing apparatus, in combination, support means; a crank turnably carried by said support means for turning movement about a predetermined axis and adapted t be connected to a door, said crank having a crank portion extending radially from said axis; a link pivotally connected at one end thereof to said crank portion of said crank and extending therefrom; a pair of substantially identical levers superposed one over the other and spaced from each other, said link extending between said levers at one of the end portions thereof; a first pivot pin extending through said one end portion of said levers and said link for pivotally connecting the latter to said levers; a second stationary pivot pin carried by said support means and extending through said levers intermediate the ends thereof, said levers having, respectively, free end portions on the side of said second pivot pin opposite from said first pivot pin; a pin located at the latter free end portions of said levers and interconnecting the same, said latter pin having a portion extending between said levers; compression spring means engaging and pressing against said latter p-in portion, said spring means being carried b-y said support means; and fluid brake means pivotally connected to the other end of said link.

9. In a door closing apparatus, in combination, support means; a crank turnably carried by said support means for turning movement about a predetermined axis and adapted to be connected to a door, said crank having a crank portion extending radially from said axis; a link pivotally connected at one end thereof to said crank portion or" said crank and extending therefrom; a pair of substantially identical levers superposed one over the other and spaced from each other, said link extending between said levers at one of the end portions thereof; a first pivot p-in extending through said one end portion of said levers and said link for pivotally connecting the latter to said levers; a second stationary pivot pin carried by said support means and extending through said levers intermediate the ends thereof, said levers having, respectively, free end portions on the side of said second pivot pin opposite from said first pivot pin; a pin located at the latter free end portions of said levers and interconnecting the same, said latter pin having a portion extending between said levers; compression spring means engaging and pressing against said latter pin portion, said spring means being carried by said support means, said levers being in the form of bell cranks; and fluid brake means pivotally connected to the other end of said link.

l0. In a door closing apparatus, in combination, support means; a crank turnably carried by said support means for turning movement about a predetermined axis and adapted to be conne/:ted to a door, said crank having a crank portion extending radially from said axis; a link pivotally connected at one end thereof to said crank portion of said crank and extending therefrom; a pair of substantially identical levers superposed one over the other and spaced from each other, said link extending between said levers at one of the end portions thereof; a first pivot pin extending through said one end portion of said levers and said link for pivotally con ecting the latter to said levers; a second stationary pivot pin carried by said l support means and extending through said levers interme- `diate the ends thereof, said levers having, respectively,

free end portions on the side of said second pivot p-in opposite from said first pivot pin; a pin located at the latter free end portions of said levers and interconnecting the same; said latter pin having a portion extending between said levers; compression spring means engaging and pressing against said latter pin portion, said spring means being carried by said support means; a pair of elongated telescoped members guiding said spring means; and fluid brake means pivotally connected to the other end of said link.

1l. In a door closing apparatus, in combination, support means; a crank turnably carried by said support means for turning movement about a predetermined axis and adapted to be connected to a door, said crank having a crank portion extending radially from said axis; a link pivotally connected at one end thereof to said crank portion of said crank and extending therefrom; a pair of substantially identical levers superposed one over the other and spaced from each other, said link extending between said levers at one of the end portions thereof; a rst pivot pin extending through said one end portions of said levers and said link for pivotally connecting the latter to said levers; a second stationary pivot pin carried by said support means and extending through said levers intermediate the ends thereof, said levers having, respectively, free end portions on the side of said second pivot pin opposite from said lirst pivot pin; a pin located at the latter free end portions of said levers and interconnecting the same; said latter pin have a portion extending between said lever; compression spring means engaging and pressing against said latter pin portion, said spring means being carried by said support means; a pair of elongated telescoped members guiding said spring means; means for releasably locking said telescoped members in a position Where said spring means is compressed to an extent which enables said spring means to be easily assembled with the remainder of the apparatus; and fluid brake means pivotally connected to the other end of said link.

12. In a door closing apparatus, in combination, support means; a crank turnably carried by said support means for turning movement about a predetermined axis and adapted to be connected to a door, said crank having a crank portion extending radially from said axis; a link pivotally connected at one end thereof to said crank portion of said crank and extending therefrom; a pair of substantially identical levers superposed one over the other and spaced from. each other, said link extending between said levers at one of the end portions thereof; a first pivot pin extending through said one end portions of said levers and said link for pivotally connecting the latter to said levers; a second stationary pivot pin carried by said support means and extending through said levers intermediate the ends thereof, said levers having, respectively, free end portions on the side of said second pivot pin opposite from said first pivot pin; a pin located at the latter free end portions of said levers and interconnecting the same, said latter pin having a portion ex tending between said lever; compression spring means engaging and pressing against said latter pin portion, said spring means being carried by said support means; a pair of elongated telescoped members guiding said spring means, one of said telescoped members having a free end portion located between said levers and formed with a recess in which said latter pin portion is located; and iiuid brake means pivotally connected to the other end of said link.

13. A door closing apparatus comprising, in combination, support means; a crank carried by said support means for turning movement about a first predetermined axis and having a crank portion extending radially from said axis; an elongated link pivotally connected at one end thereof to said crank portion; linkage means carried by said support means and being pivotally connected to said link intermediate the ends thereof, said linkage-means including a lever turnable about a second `predetermined axis .spaced from said first axis; spring means operatively'connected to said linkage means for yieldably resisting the opening of a door connected to said crank and for urging the door toward its closed position; and fluid brake means carried by said support means and pivotally connected to the other end of said link for retarding the movement `of said link.

14. A door closing apparatus as defined in claim 13 in which said fluid brake means includes an inner cylinder, a piston slidable therein, an outer cylinder coaxial with and surrounding said inner cylinder and forming an elo-ngated tubular chamber therewith, and a pair of end walls aixed to said inner cylinder, extending outwardly therefrom, and carrying said outer cylinder.

15. A door closing apparatus as defined in claim 13 in which said first and said second predetermined axes and the pivot axis of the pivoting connection between said linkage means and said link are located in a common plane when a door connected to said crank is closed.

16. A door closing apparatus as defined in claim 15 in which said elongated link has an arcuate portion which partially surrounds said crank along an angle of approximately 180 when said crank is turned through 180 from the position of said crank when a door connected thereto is closed to the position of said crank when a door connected thereto is opened.

17. A door closing apparatus as defined in claim 13 and including a rod pivotally connected at one end to said linkage means, an intermediate member interconnecting one end of said spring means with said rod, and means for adjusting the position of said intermediate member along said rod.-

18. A door closing apparatus as defined in claim 17 in which said rod has a threaded end portion distant from said one end thereof and in which said intermediate member is formed with an opening through which said threaded end portion of said rod passes, and including a nut being threadedly connected to said threaded end portion of said rod and engaging said intermediate member for adjustably determining the position of said intermediate member along said rod.

19. A door closing apparatus as defined in claim 13 in which said support means is constituted by a housing means having a pair of opposite ends, in which said crank is tumably carried by said housing means adjacent one end thereof and adapted to be connected to a door, and including adjusting means carried by said housing means at the other of said ends thereof for adjusting the elevation of said other end of said housing means with respect to said one end thereof.

20. A door closing apparatus as defined in claim 19 in which said adjusting means includes a pair of screws turnably carried by said housing means and extending beyond a lower wall thereof and a pair of discs respectively carried by said screws at the exterior of said housing means beneath said lower wall thereof.

21. A door closing apparatus as defined in claim 13 in which said lever of said linkage means is in the form of a crank member pivotally connected to said elongated link.

22. A door closing apparatus as defined in claim 21 in which an additional crank member of substantially triangular configuration is pivotally connected to said support means, said elongated link, and said linkage means.

23. A door closing apparatus comprising, in combination, support means; a crank carried by said support means for turning movement about a predetermined axis through an angle of substantially 180 and adapted to be connected to a door; linkage means including a first elongated link pivotally connected at one end. thereof to said crank and a second link pivotally connected to said first link intermediate the ends of the latter and pivotally connected to said support means for turning movement about a predetermined second axis; spring means opera tively connected at one end thereof to said second link at a point spaced from said second axis for yieldably resisting the opening of a door connected to said crank and for urging the door toward its closed position, pivot means fixed to said support means and connected to the other end of said spring means to tiltably connect said spring means to said support means, said second axis being in the closed position of the door laterally spaced froma straight line passing through said pivot means and the connection of said spring means to said second link, and during turning of said crank through an angle of said spring means being moved to an end position in which said pivot means, said second axis, and said connection between said spring means and said second link are substantially in line so that the direction of the spring force passes through said second axis, whereby the turning moment exerted by said spring force on said linkage `means and said crank becomes substantially zero at the end position of said spring means; and fluid brake means carried by said support means and pivotally connected to the other end of said first link for retarding the movement of said link.

24, A door closing apparatus comprising, in combination, support means; a crank carried by said support means for turning movement about a predetermined axis through an angle of substantially 180 and adapted to be connected to a door; linkage means including a first elongated link pivotally connected at'one end thereof to said crank and a second link pivotally connected to said first link intermediate the ends of the latter and pivotally connected to said support for turning movement about a predetermined second axis; spring means operatively connected at one end thereof to said second link at a point spaced from said second axis for yieldably resisting the opening of a door connected to said crank and for urging the door toward its closed position, said spring means and said linkage means arranged and constructed so that during turning of said crank through an angle of 180 said spring means moves from a starting position in which the turning moment exerted by the spring means on said linkage means and on said crank is at its maximum to an end position in which said turning moment becomes substantially zero; and fiuid brake means carried by said support means and pivotally connected to the other end of said first link for retarding the movement of said link.

References Cited in the file of this patent UNITED STATES PATENTS 982,008 Knapp Jan. 17, 1911 1,065,145 Koerner June 17, 1913 1,101,232 Adams lune 23, 1914 1,520,765 Norton Dec. 30, 1924 1,773,988 Garrison Aug. 26, 1930 1,898,609 Anderson Feb. 21, 1933 2,048,037 Smith July 21, 1936 2,528,904 Norballe Nov. 7, 1950 2,585,625 Carlson Feb. 12, 1952 2,700,175 Carlson Jan. 25, 1955 FOREIGN PATENTS 291,453 Switzerland Sept. 16, 1953 342,973 Great Britain Feb. 12, 1931 

